1. Field of the Invention
This invention relates to a catheter apparatus with a means for subcutaneous delivery of anesthetic agents or other fluid medicaments, and more particularly to catheter apparatus having subcutaneous infusion ports that provide for the administration of a local anesthesia or other medicaments to an area of subcutaneous tissue through which a cannula has been inserted.
2. The Present State of the Art
Catheter devices are widely used for a variety of medical applications. Generally, a catheter is a hollow, tubular cannula that is capable of being inserted into canals, vessels, passageways, or other body cavities so as to permit injection or withdrawal of fluids, or to keep a passage open. Other catheter devices are used for controlling, directing and placing medical devices, such as intubation tubes or dilation catheters, into a body cavity, such as the trachea, a blood vessel, or the heart. These types of insertion catheters are commonly referred to as intubators, insertion sheaths, and/or dilators. Given that catheters are used for such a wide variety of applications, catheters are implemented in a variety of designs, shapes and sizes. However, when used, almost all catheters share the universal characteristic of having to be passed through the skin and subcutaneous tissue of the patient so as to be inserted into the proper body cavity.
Depending on the medical procedure, the catheter is very often left in the body cavity over a relatively long period of time. As such, the skin and subcutaneous tissue through which the catheter device is inserted often becomes very swollen and tender, and thus extremely sensitive. Consequently, when the catheter is eventually retracted from the patient, the patient will often experience great discomfort. This discomfort may agitate the patient and thereby hinder the ability of medical personnel to effectively retract the catheter and/or treat the patient.
For example, in a percutaneous transluminal coronary angioplasty (PTCA) procedure, a patient is administered a local anesthesia and an intravascular sheath introducer (a type of catheter device) is inserted through the patient's skin in the groin area and into the femoral artery. In so doing, the sheath introducer necessarily passes through the area of subcutaneous tissue that lies between the skin and the femoral artery. Once inserted, the sheath introducer catheter provides a means for introducing the dilation catheter for performing the PTCA procedure.
Following the PTCA procedure, the sheath introducer is usually left within the femoral artery for a period ranging between four to twenty-four hours. Typically, the sheath is left in place because blood thinning drugs, such as Heparin, are administered to the patient. The effects of such drugs must wear off before the sheath can be removed in order to avoid hemorrhaging problems. Similarly, the device may be left in the patient as a precaution, in case quick access to the femoral artery is needed due to subsequent complications, such as an abrupt closure of the artery. In any event, by the time the sheath is retracted, the patient's skin and subcutaneous tissue through which the catheter is inserted is typically very swollen, bruised and tender. Also, by this time, the numbing effects of the earlier administered local anesthesia have completely worn off. Consequently, as the sheath is retracted from the femoral artery, the subcutaneous tissue and the overlying skin, the patient can experience considerable pain.
Pain experienced during sheath removal is known to occasionally cause vasovagal syncope type reactions, which can potentially result in a variety of undesirable patient responses--including a drop in blood pressure and heart rate. This can be hazardous when it occurs so soon after the PTCA procedure, and may thus require treatment with intravenous Atropine, or other drugs. Pain may also cause the patient to become agitated, which makes it difficult for medical personnel to properly administer arterial compression. This can lead to a hematoma formation within the subcutaneous tissue adjacent to the catheter.
Although medical personnel can administer a local anesthesia to the area, this must be done with a hypodermic needle, which usually causes as much discomfort or pain as the actual retraction of the catheter device. Thus, there is not a medical device available which adequately relieves a patient's discomfort during catheter retraction, and there is a need to be able to administer a local anesthesia to the subcutaneous tissue surrounding a catheter device prior to the retraction of the device, in a relatively painless and easy manner.